In a wireless communications system, signals are sent from a transmitter to a receiver through a medium known as a wireless communications channel. In practice, signals arrive at the receiver by a number of different paths, and the associated channel is referred to as a multipath channel. Various signal processing techniques are employed to reduce interference and/or noise in signals received through multipath channels, such as filtering. Some signal processing techniques, however, require information about the multipath channel to effectively process the signal. Processing a received signal using a Wiener filter, for example, requires knowledge of channel statistics characterizing the multipath channel.
Wireless channels can be characterized by a number of different channel statistics, such as those defined by a power delay profile, a Doppler spectrum, and power angular spectrum. Channel statistics, however, change over time, frequency, and space, and generally cannot be assumed static for a relatively large time scale, for example, the time for transmitting multiple packets or on the order of tens of milliseconds. Accordingly, signal processing techniques may perform sub-optimally in contexts in which channel statistics are rapidly, and continuously, changing.